三峡库区吸附态磷负荷空间分布的模拟研究

发布时间：2018-04-27 12:26

本文选题：三峡库区 + 降雨侵蚀力　；参考：《重庆大学》2015年硕士论文

【摘要】：磷是造成水体富营养化的主要原因,随着降雨引起的土壤侵蚀而产生的吸附态磷污染是磷污染的主要形式。三峡库区地处长江流域,人口密集,由于降雨丰沛且集中,暴雨较多,以及特殊的地形、土壤特性和不合理的耕作方式,使其产生大量的土壤流失,导致严重的吸附态磷污染。因此,开展对库区非点源污染时空分布特性的研究具有重要的理论和实际意义。鉴于三峡库区吸附态磷污染负荷的季节性空间分布鲜有报道,本研究构建了吸附态磷污染负荷的空间分布模型,并应用所构建的模型对三峡库区季节性吸附态磷负荷的空间分进行了模拟。主要的研究成果为:①吸附态磷负荷空间分布模型的构建综合考虑地形特征和植被覆盖对被侵蚀土壤迁移的影响,引入时空分布的地形指数因子和植被覆盖管理因子,提出具有空间分布特性的入河系数的计算方法。将改进的土壤流失方程作为土壤侵蚀量的计算方程,结合所提出的入河系数并考虑磷在土壤中的富集,构建吸附态磷负荷的空间分布模型。以三峡库区作为案例,对该区域2000~2010年的吸附态磷负荷的空间分布进行了模拟,并以库区内小江流域和大宁河流域的实测值进行验证,其模拟值与实测值吻合较好,表明所构建的模型以及所提出的入河系数的计算方法可行。②库区季节性降雨侵蚀力的空间分布特性研究基于日降雨量模型,利用三峡库区内部及其周边23个基准气象站点的日降雨资料,对2000~2010年三峡库区的降雨侵蚀力进行模拟计算,得到三峡库区季节性降雨侵蚀力的空间分布和年均降雨侵蚀力的空间分布。库区降雨侵蚀力年际差异非常显著,降雨侵蚀力的最大值出现在2007年,达到9482 MJmm/(hm2h),2001的降雨侵蚀力值最小,仅有6133MJmm/(hm2h);一年中降雨量和降雨侵蚀力的年内变化非常明显且变化趋势一致,7月份达到最大值,降雨侵蚀力为1700MJmm/(hm2h),1月份最小,为64 MJmm/(hm2h);降雨侵蚀主要发生在夏季,夏季较大的区域主要分布在开县、夷陵区和北碚等区域;冬季最小,冬季较大的区域主要分布在开县附近。③库区季节性吸附态磷污染负荷的空间分布模拟运用所构建的吸附态磷负荷空间分布模型,模拟计算得到三峡库区季节性吸附态磷污染负荷的空间分布和年均吸附态磷污染负荷的空间分布。吸附态磷污染负荷在时间和空间上的分布结构极不平衡,夏季的吸附态磷污染负荷最严重,整个库区在夏季产生的吸附态磷负荷总量为4.7×103t,占到全年吸附态磷负荷总量的50%;冬季最轻,库区在冬季产生的吸附态总磷负荷达到0.2×103 t,只占到全年吸附态磷负荷总量的2.1%;整个库区的年均吸附态总磷负荷为9.4×103 t。年均吸附态磷污染负荷从整体上来说,最严重的区域分布在秭归西北部、奉节、云阳、开县以及武隆地区,而在最东部夷陵地区和最西部江津等地区吸附态磷污染负荷较轻。④不同管理措施下吸附态磷负荷空间分布预测运用所构建的模型,分别对三峡库区内不同管理措施下的土壤侵蚀和吸附态磷负荷进行预测。本研究所采取的管理措施为:(1)减少30%的施肥量;(2)把坡度大于25°的耕地退耕还草;(3)把坡度大于25°的耕地退耕还林。通过预测得知,退耕还林对土壤侵蚀和吸附态磷负荷的消减量比退耕还草对二者的消减量要大。退耕还林对土壤侵蚀和吸附态磷负荷的消减率的分别为33.39%和24.17%,退耕还草对二者的消减率分别为20.17%和12.38%,减少30%的施肥量对吸附态磷负荷总量的消减率为17.1%。
[Abstract]:Phosphorus is the main cause of eutrophication. The phosphorus pollution caused by soil erosion caused by rainfall is the main form of phosphorus pollution. The Three Gorges Reservoir area is located in the Yangtze River Basin and is densely populated. Because of the heavy rainfall and concentration, heavy rain, and special terrain, soil characteristics and unreasonable farming methods, make it produce large scale. Therefore, it is of great theoretical and practical significance to study the spatial and temporal distribution characteristics of non point source pollution in the reservoir area. In view of the seasonal spatial distribution of the phosphorus pollution load in the Three Gorges Reservoir area, the spatial distribution model of the adsorbed phosphorus pollution load is constructed. The spatial distribution of seasonal adsorption phosphorus load in the Three Gorges Reservoir area is simulated with the model constructed. The main research results are as follows: (1) the construction of the spatial distribution model of adsorbed phosphorus load considers the effects of topographic features and vegetation cover on the migration of the eroded soil, and introduces the spatial and temporal distribution of topographic index and vegetation coverage. A calculation method of the river entry coefficient with spatial distribution characteristics is proposed. The improved soil loss equation is used as the calculation equation of soil erosion amount. The spatial distribution model of the adsorbed phosphorus load is constructed by combining the proposed River entry coefficient and the accumulation of phosphorus in the soil. The Three Gorges Reservoir area is used as a case for the 2000~201 area. The spatial distribution of the adsorbed phosphorus load in 0 years is simulated and verified by the measured values of the Xiaojiang River Basin and the great Ninghe basin in the reservoir area. The simulated values are in good agreement with the measured values. The results show that the proposed model and the proposed method of calculating the river entry coefficient are feasible. Based on the daily rainfall model of the Three Gorges Reservoir area, the rainfall erosivity of the Three Gorges Reservoir Area in 2000~2010 is simulated by the daily rainfall data of 23 datum meteorological stations in the Three Gorges Reservoir area. The spatial distribution of seasonal rainfall erosivity and the spatial distribution of annual rainfall erosivity in the Three Gorges Reservoir Area are obtained. The interannual difference of Rainfall Erosivity in the reservoir area is obtained. The maximum rainfall erosivity occurred in 2007, reaching 9482 MJ? Mm/ (hm2? H), and 2001 of the rainfall erosivity minimum, only 6133MJ? Mm/ (hm2? H); the annual changes in rainfall and rainfall erosivity in a year were very obvious and consistent, and reached the maximum in July, and the rainfall erosivity was 1700MJ? Mm/ (hm2 h), and the smallest in January, for January. 64 MJ? Mm/ (hm2? H); rainfall erosion mainly occurs in summer, the larger regions in summer are mainly distributed in Kaixian, Yiling and Beibei regions; winter is the smallest, and the larger regions in winter are mainly distributed near Kaixian. The spatial distribution of seasonal adsorptive phosphorus pollution load in the Three Gorges Reservoir area and the spatial distribution of annual average adsorption phosphorus pollution load in the Three Gorges Reservoir area are calculated. The distribution structure of the adsorbed phosphorus pollution load in time and space is extremely unbalanced, the adsorption phosphorus pollution load is the most serious in summer, and the total adsorption phosphorus load in the whole reservoir area in summer is total. The amount is 4.7 x 103t, accounting for 50% of the total phosphorus load in the whole year, the lightest in winter, the total phosphorus load of the reservoir area in winter is 0.2 * 103 T, accounting for only 2.1% of the total phosphorus load in the whole year, and the annual average adsorptive total phosphorus load of the whole reservoir area is 9.4 * 103 T. per year. The region is distributed in the northwest of Zigui, Fengjie, Yunyang, Kaixian and Wulong, while the phosphorus pollution load in the most eastern Yiling area and the most western region of Jiangjin is lighter. The management measures of corrosion and adsorbed phosphorus were predicted. The management measures adopted in this study were as follows: (1) reducing the amount of fertilizer by 30%; (2) returning farmland to cultivated land with gradient over 25 degrees; (3) reforestation of cultivated land with slope greater than 25 degrees. Through prediction, the reduction of soil erosion and adsorbed phosphorus load by returning farmland to forest was less than the reduction of two of cultivated land to two. The reduction rate of soil erosion and adsorption state phosphorus load of returning farmland to forest was 33.39% and 24.17% respectively, and the reduction rate of returning cultivated land to two were 20.17% and 12.38% respectively. The reduction rate of 30% fertilizer amount to the total load of adsorbed phosphorus was 17.1%..

【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S157

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